Spectroscope

ABSTRACT

A spectrometer 1A includes a package 2 having a stem 4 and a cap 5, an optical unit 10A disposed on the stem 4, and a lead pin 3 for securing the optical unit 10A to the stem 4. The optical unit 10A includes a dispersive part 21 for dispersing and reflecting light entering from a light entrance part 6 of the cap 5, a light detection element 30 having a light detection part 31 for detecting the light dispersed and reflected by the dispersive part 21, a support 40 for supporting the light detection element 30 such that a space is formed between the dispersive part 21 and the light detection element 30, and a projection 11 protruding from the support 40, the lead pin 3 being secured to the projection 11. The optical unit 10A is movable with respect to the stem 4 in a contact part of the optical unit 10A and the stem 4.

TECHNICAL FIELD

The present invention relates to a spectrometer which disperses anddetects light.

BACKGROUND ART

For example, Patent Literature 1 discloses a spectrometer including alight entrance part, a dispersive part for dispersing and reflectinglight incident thereon from the light entrance part, a light detectionelement for detecting the light dispersed and reflected by thedispersive part, and a box-shaped support for supporting the lightentrance part, dispersive part, and light detection element.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Publication No.2000-298066

SUMMARY OF INVENTION Technical Problem

Incidentally, the above-described spectrometer has a problem of awavelength-temperature dependency in which a positional relationshipbetween a dispersive part and a light detection part of a lightdetection element varies and a peak wavelength of detected light isshifted as a result of expansion and contraction of a material due to atemperature change of an environment in which the spectrometer is used,heating in the light detection part of the light detection element, etc.When the amount of the shifted peak wavelength (wavelength shift amount)of the detected light becomes large, there is concern that detectionaccuracy of the spectrometer decreases.

In this regard, an object of the present invention is to provide aspectrometer capable of suppressing a decrease in detection accuracy.

Solution to Problem

A spectrometer in accordance with one aspect of the present inventionincludes a package having a stem and a cap provided with a lightentrance part, an optical unit disposed on the stem inside the package,and a fixing member configured to secure the optical unit to the stem,wherein the optical unit includes a dispersive part configured todisperse and reflect light entering the package from the light entrancepart, a light detection element having a light detection part configuredto detect the light dispersed and reflected by the dispersive part, asupport configured to support the light detection element such that aspace is formed between the dispersive part and the light detectionelement, and a projection protruding from the support, the fixing memberbeing secured to the projection, and the optical unit is movable withrespect to the stem in a contact part of the optical unit and the stem.

In the spectrometer, the optical unit is disposed on the stem inside thepackage. In this way, it is possible to suppress a decrease in detectionaccuracy resulting from deterioration of a member, etc. In addition, theoptical unit is positioned with respect to the package by the fixingmember. Meanwhile, the optical unit is movable with respect to the stemin the contact part of the optical unit and the stem. That is, theoptical unit is not secured to the stem by adhesion, etc. In this way,it is possible to mitigate residual stress or stress between the stemand the optical unit resulting from expansion and contraction of thestem due to a temperature change of an environment in which thespectrometer is used, heating in the light detection element, etc., andto suppress occurrence of a variation in positional relationship betweenthe dispersive part and the light detection part of the light detectionelement. Therefore, the spectrometer may reduce a wavelength shiftamount resulting from expansion and contraction of a material of thespectrometer, and suppress a decrease in detection accuracy.

In the spectrometer in accordance with one aspect of the presentinvention, the dispersive part may be included in a dispersive elementby being provided on a substrate, the support may include a base wallpart disposed to oppose the stem, the light detection element beingfixed to the base wall part, and a side wall part disposed to erect froma side of the dispersive part to the stem, the side wall part supportingthe base wall part, and the side wall part may be joined to thesubstrate in a portion of a contact part of the side wall part and thesubstrate. According to this configuration, when the side wall part ofthe support is joined to the substrate in a portion of the contact partof the side wall part and the substrate, the dispersive part isappropriately positioned with respect to the light detection elementsecured to the base wall part. Meanwhile, the side wall part is notfully joined to the substrate, and thus stress or residual stressmutually applied to the support and the substrate due to expansion andcontraction is mitigated. In this way, it is possible to suppress aposition shift between the dispersive part and the light detectionelement, and to further reduce a wavelength shift amount resulting fromexpansion and contraction of the material of the spectrometer.

In the spectrometer in accordance with one aspect of the presentinvention, the side wall part may include a first wall part and a secondwall part opposing each other, the first wall part may be joined to thesubstrate in at least a portion of a contact part of the first wall partand the substrate, and the second wall part may be movable with respectto the substrate in a contact part of the second wall part and thesubstrate. According to this configuration, a configuration of thesupport may be simplified and a positional relationship of the supportwith respect to the substrate may be stabilized by the first wall partand the second wall part provided to oppose each other with thedispersive part interposed therebetween. Further, when at least aportion of only one of the wall parts of the support (first wall part)is joined to the substrate (one side joint), it is possible to reliablyposition the support with respect to the substrate, and to mitigatestress or residual stress mutually applied to the support and thesubstrate due to expansion and contraction.

In the spectrometer in accordance with one aspect of the presentinvention, an area of the contact part of the first wall part and thesubstrate may be larger than an area of the contact part of the secondwall part and the substrate. According to this configuration, it ispossible to mitigate stress or residual stress mutually applied to thesupport and the substrate due to expansion and contraction whilesecuring a sufficient area for joining the support to the substrate.

In the spectrometer in accordance with one aspect of the presentinvention, an area of the contact part of the first wall part and thesubstrate may be smaller than an area of the contact part of the secondwall part and the substrate. According to this configuration, it ispossible to further mitigate stress or residual stress mutually appliedto the support and the substrate due to expansion and contraction bysuppressing an area for joining the support to the substrate.

In the spectrometer in accordance with one aspect of the presentinvention, the first wall part and the second wall part may oppose eachother in a direction parallel to a direction in which the lightdetection part is shifted from the dispersive part when viewed in adirection in which the stem and the base wall part oppose each other.According to this configuration, it is possible to simplify amanufacturing operation for providing the light detection element on thesupport, and to effectively use a free space on the substrate.

In the spectrometer in accordance with one aspect of the presentinvention, the dispersive part may be included in a dispersive elementby being provided on a substrate, the support may include a base wallpart disposed to oppose the stem, the light detection element beingfixed to the base wall part, and a side wall part disposed to erect froma side of the dispersive part to the stem, the side wall part supportingthe base wall part, the side wall part may include a first wall part anda second wall part opposing each other in a direction perpendicular to adirection in which the light detection part is shifted from thedispersive part when viewed in a direction in which the stem and thebase wall part oppose each other, and the side wall part may be joinedto the substrate in at least a portion of a contact part of the sidewall part and the substrate. According to this configuration, the firstwall part and the second wall part are provided to oppose each other ina direction in which an influence on a wavelength shift amount is smallwhen a position shift occurs. Thus, it is possible to further reduce awavelength shift amount resulting from stress or residual stressmutually applied to the support and the substrate due to expansion andcontraction.

Advantageous Effects of Invention

According to the present invention, it is possible to provide aspectrometer capable of suppressing a decrease in detection accuracy.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional view of a spectrometer in accordance with a firstembodiment of the present invention;

FIG. 2 is a sectional view taken along the line II-II of FIG. 1 and seenas a side view;

FIG. 3 is a sectional view taken along the line III-III of FIG. 1 andseen as a plan view;

FIG. 4 is a bottom view of a support of the spectrometer of FIG. 1;

FIG. 5 is a bottom view of a support of a modified example of thespectrometer of FIG. 1;

FIG. 6 is a bottom view of a support of a modified example of thespectrometer of FIG. 1;

FIG. 7 is a sectional view of a spectrometer in accordance with a secondembodiment of the present invention;

FIG. 8 is a sectional view taken along the line VIII-VIII of FIG. 7 andseen as a side view;

FIG. 9 is a bottom view of a support of the spectrometer of FIG. 7;

FIG. 10 is a sectional view of a spectrometer in accordance with a thirdembodiment of the present invention seen as a side view;

FIG. 11 is a sectional view of a spectrometer in accordance with afourth embodiment of the present invention;

FIG. 12 is a sectional view taken along the line XII-XII of FIG. 11 andseen as a side view;

FIG. 13 is a bottom view of a support of the spectrometer of FIG. 11;

FIG. 14 is a sectional view of a spectrometer in accordance with a fifthembodiment of the present invention;

FIG. 15 is a sectional view taken along the line XV-XV of FIG. 14 andseen as a side view;

FIG. 16 is a bottom view of a support of the spectrometer of FIG. 14;and

FIG. 17 is a bottom view of a support of a modified example of thespectrometer of FIG. 14.

DESCRIPTION OF EMBODIMENTS

In the following, preferred embodiments of the present invention will beexplained in detail with reference to the drawings. In the drawings, thesame or equivalent parts will be referred to with the same signs whileomitting their overlapping descriptions.

First Embodiment

As illustrated in FIGS. 1 and 2, a spectrometer 1A includes a package 2having a structure of a CAN package, an optical unit 10A contained inthe package 2, and a plurality of lead pins (fixing members) 3. Thepackage 2 has a rectangular plate-like stem 4 made of a metal and a cap5 shaped into a rectangular parallelepiped box made of a metal. The stem4 and the cap 5 are joined to each other airtightly while a flange part4 a of the step 4 and a flange part 5 a of the cap 5 are in contact witheach other. By way of example, the stem 4 and the cap 5 are airtightlysealed to each other in a vacuum atmosphere or a nitrogen atmosphereunder dew point management (e.g., at −55° C.). In this way, it ispossible to suppress a decrease in detection accuracy resulting fromdeterioration of a member in the package 2 due to moisture, occurrenceof condensation in the package 2 due to a decrease in ambienttemperature, etc. For example, one side of the package 2 has a length ofabout 10 to 20 mm.

In the cap 5, a wall part 5 b opposing the stem 4 is provided with alight entrance part 6 for letting light L1 into the package 2 from theoutside thereof. The light entrance part 6 is constructed by airtightlyjoining a window member 7 having a disk or rectangular plate form to aninner surface of the wall part 5 b so that the window member 7 covers alight transmission hole 5 c having a circular cross section formed inthe wall part 5 b. The window member 7 is made of a material whichtransmits the light L1 therethrough, examples of which include silica,borosilicate glass (BK7), Pyrex (registered trademark) glass, and Kovarglass. Silicon and germanium are also effective for infrared rays. Thewindow member 7 may also be provided with an AR (Anti Reflection) coat.The window member 7 may further have such a filter function as totransmit therethrough only a predetermined wavelength of light. Inaddition, when the window member 7 is formed by welding Kovar glass,etc. to the inner surface of the wall part 5 b, Kovar glass, etc. maymove into the light transmission hole 5 c to fill the light transmissionhole 5 c.

Each lead pin 3 penetrates through the stem 4 while being arranged in athrough hole 4 b of the stem 4. Each lead pin 3 is made of a metalconstructed by applying nickel plating (1 to 10 μm) and gold plating(0.1 to 2 μm) and the like to Kovar metal, for example, and extends inthe direction in which the light entrance part 6 and the stem 4 opposeeach other (hereinafter referred to as “Z-axis direction”). Each leadpin 3 is secured to the through hole 4 b through a hermetic seal membermade of glass for sealing such as low-melting glass havingelectrically-insulating and light-shielding properties. In each of apair of side edge parts of the rectangular-plate-shaped stem 4 opposingeach other in a direction (hereinafter referred to as “Y-axisdirection”) perpendicular to its longitudinal direction (hereinafterreferred to as “X-axis direction”) and Z-axis direction, a plurality ofthrough holes 4 b are arranged in a row along the X-axis direction.

The optical unit 10A is arranged on the stem 4 within the package 2. Theoptical unit 10A has a dispersive element 20, a light detection element30, and a support 40. The dispersive element 20 is provided with adispersive part 21, which disperses and reflects the light L1 enteringthe package 2 from the light entrance part 6. The light detectionelement 30 detects light L2 dispersed and reflected by the dispersivepart 21. The support 40 supports the light detection element 30 so as toform a space between the dispersive part 21 and the light detectionelement 30.

The dispersive element 20 has a substrate 22 having a rectangular plateform made of silicon, plastic, ceramic, glass, or the like. In thesubstrate 22, a surface 22 a on the light entrance part 6 side is formedwith a depression 23 having a curved inner surface. A molded layer 24 isarranged on the surface 22 a of the substrate 22 so as to cover thedepression 23. The molded layer 24 is formed into a film along the innersurface of the depression 23 and has a circular form when viewed in theZ-axis direction.

A grating pattern 24 a corresponding to a blazed grating having aserrated cross section, a binary grating having a rectangular crosssection, a holographic grating having a sinusoidal cross section, or thelike is formed in a predetermined region of the molded layer 24. Thegrating pattern 24 a is constructed by a plurality of grating groovesalong the X-axis direction, each extending in the Y-axis direction whenviewed in the Z-axis direction. This molded layer 24 is formed bypressing a mold die against a molding material (e.g., photocuring epoxyresins, acrylic resins, fluorine-based resins, silicone, and replicaoptical resins such as organic/inorganic hybrid resins) and curing themolding material (e.g., by photocuring or thermal curing) in this state.

A reflecting film 25, which is a vapor-deposited film made of Al, Au, orthe like, is formed on a surface of the molded layer 24 so as to coverthe grating pattern 24 a. The reflecting film 25 is formed along a shapeof the grating pattern 24 a. A surface on the light entrance part 6 ofthe reflecting film 25 formed along the shape of the grating pattern 24a serves as the dispersive part 21 in the form of a reflection grating.As in the foregoing, the dispersive part 21 is provided on the substrate22, so as to construct the dispersive element 20.

The light detection element 30 has a substrate 32 having a rectangularplate form made of a semiconductor material such as silicon. Thesubstrate 32 is formed with a slit 33 extending in the Y-axis direction.The slit 33 is located between the light entrance part 6 and thedispersive part 21 and transmits therethrough the light L1 entering thepackage 2 from the light entrance part 6. In the slit 33, an end part onthe light entrance part 6 side widens toward the light entrance part 6in each of the X- and Y-axis directions.

In the substrate 32, a surface 32 a on the dispersive part 21 side isprovided with a light detection part 31 in juxtaposition with the slit33 along the X-axis direction. The light detection part 31 isconstructed as a photodiode array, a C-MOS image sensor, a CCD imagesensor, or the like. The surface 32 a of the substrate 32 is providedwith a plurality of terminals 34 for inputting/outputting electricsignals to/from the light detection part 31. The X-axis direction is adirection parallel to a direction in which the light detection part 31is shifted from the dispersive part 21 when viewed in the Z-axisdirection. Herein, the phrase “the light detection part 31 is shiftedfrom the dispersive part 21” means that a region of the light detectionpart 31 not overlapping the dispersive part 21 is present when viewed inthe Z-axis direction. That is, the phrase “the direction in which thelight detection part 31 is shifted from the dispersive part 21” means adirection in which a region of the light detection part 31 notoverlapping the dispersive part 21 is present with respect to thedispersive part 21 when viewed in the Z-axis direction. This directionis the same as a direction in which the light detection part 31 isprovided with respect to the slit 33 when viewed in the Z-axisdirection. In addition, the X-axis direction is a direction in which thegrating grooves of the grating pattern 24 a are arranged, and is adirection in which photodiodes are arranged in the light detection part31. Meanwhile, the Y-axis direction is a direction perpendicular to adirection in which the light detection part 31 is shifted from thedispersive part 21 (X-axis direction) when viewed in the Z-axisdirection.

The support 40 is a hollow structure including a base wall part 41arranged so as to oppose the stem 4 in the Z-axis direction, and a sidewall part (first wall part) 42 and a side wall part (second wall part)43 arranged so as to oppose each other in the X-axis direction. The sidewall part 43 is disposed on a side on which the light detection part 31is provided with respect to the slit 33. The side wall part 42 isprovided on the opposite side from the side on which the light detectionpart 31 is provided with respect to the slit 33. A width of the sidewall part 42 is larger than a width of the side wall part 43. The sidewall parts 42 and 43 are disposed to erect from a side of the dispersivepart 21 to the stem 4, and support the base wall part 41 at both sidesinterposing the dispersive part 21 therebetween in the X-axis direction.

The light detection element 30 is secured to the base wall part 41. Thelight detection element 30 is secured to the base wall part 41 bybonding a surface 32 b of the substrate 32 on the side opposite from thedispersive part 21 to an inner surface 41 a of the base wall part 41.That is, the light detection element 30 is arranged on the stem 4 sideof the base wall part 41.

The base wall part 41 is formed with a light transmission hole (lighttransmission part) 46 for communicating the inside and outside spaces ofthe support 40 in the form of a hollow structure to each other. Thelight transmission hole 46 is located between the light entrance part 6and the slit 33 of the substrate 32 and transmits therethrough the lightL1 entering the package 2 from the light entrance part 6. The lighttransmission hole 46 widens toward the light entrance part 6 in each ofthe X- and Y-axis directions. When viewed in the Z-axis direction, thelight transmission hole 5 c of the light entrance part 6 includes thelight transmission hole 46 as a whole. In addition, when viewed in theZ-axis direction, the light transmission hole 46 includes the slit 33 asa whole.

As illustrated in FIG. 1, FIG. 2, and FIG. 4, at both end sides of aside surface 42 a forming an inner end part of the side wall part 42 inthe Y-axis direction, projections 42 b are formed to protrude to a sideat which the dispersive part 21 is disposed with respect to the sidesurface 42 a (that is, the inside of the support 40 which is a hollowstructure). The projections 42 b extend in the Z-axis direction.Similarly, at both end sides of a side surface 43 a forming an inner endpart of the side wall part 43 in the Y-axis direction, projections 43 bare formed to protrude to a side at which the dispersive part 21 isdisposed with respect to the side surface 43 a (that is, the inside ofthe support 40 which is a hollow structure). The projections 43 b extendin the Z-axis direction. When the projections 42 b and 43 b are formedin the side wall parts 42 and 43, positioning of the support 40 withrespect to the substrate 22 is stabilized.

As illustrated in FIGS. 2 and 3, the optical unit 10A further includesprojections 11 projecting from the support 40. Each projection 11 isarranged at such a position as to be separated from the stem 4. Theprojection 11 projects from an end part of each side wall part (the sidewall part 42 and the side wall part 43) on the side opposite from thestem 4 to the side opposite from the dispersive part 21 in the Y-axisdirection (i.e., the outside of the support 40 in the form of a hollowstructure) and extends in the X-axis direction to connect end parts ofthe side wall part 42 and the side wall part 43 in the Y-axis direction.In the optical unit 10A, the outer surface 41 b of the base wall part 41and the surface 11 a of the projection 11 on the side opposite from thestem 4 are substantially flush with each other.

As illustrated in FIGS. 1 and 2, in the optical unit 10A, a surface 22 bof the substrate 22 of the dispersive element 20 on the stem 4 sidetouches an inner surface 4 c of the stem 4. However, the surface 22 b ofthe substrate 22 is not secured to the inner surface 4 c of the stem 4by adhesion, etc. That is, the optical unit 10A is movable with respectto the stem 4 in a contact part of the optical unit 10A and the stem 4(a portion in which the surface 22 b of the substrate 22 touches theinner surface 4 c of the stem 4).

The surface 22 a of the substrate 22 touches a bottom face 42 ccorresponding to an end part of the side wall part 42 on the stem 4 sideand a bottom face 43 c corresponding to an end part of the side wallpart 43 on the stem 4 side. For example, the bottom face 42 c of theside wall part 42 is attached and joined to the surface 22 a of thesubstrate 22 using an adhesive material such as epoxy resin, acrylicresin, silicone, organic/inorganic hybrid resin, a paste resin such assilver paste resin, etc. In this way, the substrate 22 is positionedwith respect to the support 40. On the other hand, the bottom face 43 cof the side wall part 43 is not joined to the surface 22 a of thesubstrate 22. That is, the side wall part 43 is movable with respect tothe substrate 22 in a contact part of the side wall part 43 and thesubstrate 22 (a portion in which the bottom face 43 c of the side wallpart 43 touches the surface 22 a of the substrate 22). A method ofjoining the bottom face 42 c of the side wall part 42 to the surface 22a of the substrate 22 is not restricted to the above-described attachingand joining. For example, the bottom face 42 c of the side wall part 42may be joined to the surface 22 a of the substrate 22 using welding ordirect bonding.

As illustrated in FIG. 4, the optical unit 10A further includes a wiring12 provided in the support 40. The wiring 12 includes a plurality offirst terminal parts 12 a, a plurality of second terminal parts 12 b,and a plurality of connection parts 12 c. The first terminal parts 12 aare arranged on the inner surface 41 a of the base wall part 41 andexposed to the inner space of the support 40. The second terminal parts12 b are arranged on the surfaces 11 a of the projections 11 and exposedto the space on the outside of the support 40 but inside of the package2. The connection parts 12 c, each connecting its corresponding firstand second terminal parts 12 a and 12 b to each other, are embedded inthe support 40.

The wiring 12 is provided in the base wall part 41, side wall parts 42and 43, and projections 11, which are integrally formed, so as toconstruct a molded interconnect device (MID). In this case, the basewall part 41, side wall parts 42 and 43, and projections 11 are made ofa molding material, examples of which include ceramics such as AlN andAl₂O₃, resins such as LCP, PPA, and epoxy, and glass for molding.

The terminals 34 of the light detection element 30 secured to the basewall part 41 are electrically connected to their corresponding firstterminal parts 12 a of the wiring 12. The terminal 34 of the lightdetection element 30 and the first terminal part 12 a of the wiring 12corresponding to each other are electrically connected to each other bywire bonding using wires 8.

As illustrated in FIGS. 2 and 3, the lead pins 3 penetrating through thestem 4 are electrically connected to their corresponding second terminalparts 12 b of the wiring 12. Each lead pin 3 is provided with aflange-shaped stopper 3 a. The lead pins 3 extend to the projections 11arranged at such positions as to be separated from the stem 4 and areinserted through their corresponding through holes 11 c of theprojections 11 while the stoppers 3 a are in contact with theprojections 11 from the stem 4 side (i.e., while the stoppers 3 a are incontact with the surfaces 11 b on the stem 4 side of the projections11). Each second terminal part 12 b surrounds its corresponding throughhole 11 c on the surface 11 a of the projection 11. In this state, thelead pin 3 and the second terminal part 12 b of the wiring 12corresponding to each other are electrically connected to each otherwith a conductive resin, solder, a gold wire, or the like. Here, thelead pins 3 include those simply secured to the through holes 4 b of thestem 4 and the through holes 11 c of the projections 11 but notelectrically connected to the wiring 12. The optical unit 10A ispositioned with respect to the package 2 by the lead pins 3.

In thus constructed spectrometer 1A, as illustrated in FIG. 1, the lightL1 enters the package 2 from the light entrance part 6 thereof andpasses through the light transmission hole 46 of the base wall part 41and the slit 33 of the light detection element 30 in sequence, therebycoming into the inner space of the support 40. The light L1 entering theinner space of the support 40 reaches the dispersive part 21 of thedispersive element 20 and is dispersed and reflected by the dispersivepart 21. The light L2 dispersed and reflected by the dispersive part 21reaches the light detection part 31 of the light detection element 30and is detected by the light detection element 30. At this time,electric signals are inputted to and outputted from the light detectionpart 31 of the light detection element 30 through the terminals 34 ofthe light detection element 30, the wires 8, the wiring 12, and the leadpins 3.

A method for manufacturing the spectrometer 1A will now be explained.First, a molded interconnect device provided with the integrally formedbase wall part 41, side wall parts 42 and 43, and projections 11 withthe wiring 12 is prepared. Subsequently, as illustrated in FIG. 4, thelight detection element 30 is bonded to the inner surface 41 a of thebase wall part 41 of the support 40 with reference to alignment marks 47provided on the inner surface 41 a. Then, the terminal 34 of the lightdetection element 30 and the first terminal part 12 a of the wiring 12corresponding to each other are electrically connected to each other bywire bonding with the wires 8. Thereafter, the surface 22 a of thesubstrate 22 coming into contact with the bottom face 42 c is bonded tothe bottom face 42 c of the side wall part 42 with reference toalignment marks 48 provided on the respective bottom faces 42 c and 43 cof the side wall parts 42 and 43 of the support 40.

In thus manufactured optical unit 10A, the dispersive part 21 and thelight detection part 31 are accurately positioned with respect to eachother in the X- and Y-axis directions by mounting with reference to thealignment marks 47 and 48. The dispersive part 21 and the lightdetection part 31 are also accurately positioned with respect to eachother in the Z-axis direction by the difference in level between thebottom faces 42 c and 43 c of the side wall part 42 and 43 and the innersurface 41 a of the base wall part 41. Here, the slit 33 and the lightdetection part 31 are accurately positioned with respect to each otherin the light detection element 30 during its manufacturing. Therefore,the optical unit 10A becomes one in which the slit 33, dispersive part21, and light detection part 31 are accurately positioned with respectto each other.

Next, as illustrated in FIGS. 2 and 3, the stem 4 having the lead pins 3secured to the through holes 4 b is prepared. Then, the optical unit 10Ais positioned with respect to (secured to) the inner surface 4 c of thestem 4 while inserting the lead pins 3 into the through holes 11 c ofthe projections 11 of the optical unit 10A. Subsequently, the lead pin 3and the second terminal part 12 b of the wiring 12 corresponding to eachother are electrically connected to each other with a conductive resin,solder, a gold wire, or the like. Then, as illustrated in FIGS. 1 and 2,the cap 5 provided with the light entrance part 6 is prepared, and thestem 4 and cap 5 are airtightly joined to each other. The foregoingmanufactures the spectrometer 1A.

Effects produced by the spectrometer 1A will now be explained. First, inthe spectrometer 1A, the optical unit 10A is disposed on the stem 4inside the package 2. In this way, it is possible to suppress a decreasein detection accuracy resulting from deterioration of a member in thepackage 2 due to moisture, occurrence of condensation in the package 2due to a decrease in ambient temperature, etc. In addition, the opticalunit 10A is positioned with respect to the package 2 by the lead pins 3.Meanwhile, the optical unit 10A is movable with respect to the stem 4 inthe contact part of the optical unit 10A and the stem 4. That is, theoptical unit 10A is not secured to the stem 4 by adhesion, etc. In thisway, it is possible to mitigate residual stress or stress between thestem 4 and the optical unit 10A resulting from expansion and contractionof the stem 4 due to a temperature change of an environment in which thespectrometer 1A is used, heating in the light detection part 31 of thelight detection element 30, etc., and to suppress occurrence of avariation in positional relationship between the dispersive part 21 andthe light detection part 31 of the light detection element 30.Therefore, the spectrometer 1A may reduce a wavelength shift amountresulting from expansion and contraction of a material of thespectrometer 1A, and suppress a decrease in detection accuracy.

In addition, when the side wall parts 42 and 43 of the support 40 arejoined to the substrate 22 in a portion (a portion in which the surface22 a of the substrate 22 touches the bottom face 42 c of the side wallpart 42) of the contact part of the side wall parts 42 and 43 and thesubstrate 22 (a portion in which the surface 22 a of the substrate 22touches the bottom faces 42 c and 43 c of the side wall parts 42 and43), the dispersive part 21 is appropriately positioned with respect tothe light detection element 30 secured to the base wall part 41.Meanwhile, the side wall part 43 of the support 40 is not fully joinedto the substrate 22, and thus stress or residual stress mutually appliedto the support 40 and the substrate 22 due to expansion and contractionis mitigated. In this way, it is possible to suppress a position shiftbetween the dispersive part 21 and the light detection element 30, andto further reduce a wavelength shift amount resulting from expansion andcontraction of the material of the spectrometer 1A.

In addition, a configuration of the support 40 may be simplified and apositional relationship of the support 40 with respect to the substrate22 may be stabilized by the side wall part 42 and the side wall part 43provided to oppose each other with the dispersive part 21 interposedtherebetween. Further, when at least a portion of only one of the sidewall parts 42 and 43 of the support 40 (for example, the side wall part42 in the present embodiment) is joined to the substrate 22 (one sidejoint), it is possible to reliably position the support 40 with respectto the substrate 22, and to mitigate stress or residual stress mutuallyapplied to the support 40 and the substrate 22 due to expansion andcontraction.

In addition, an area of a contact part of the side wall part 42 and thesubstrate 22 joined to each other by adhesion, etc. is larger than anarea of a contact part of the side wall part 43 and the substrate 22 notjoined to each other. Thus, it is possible to mitigate stress orresidual stress mutually applied to the support 40 and the substrate 22due to expansion and contraction while securing a sufficient area forjoining the support 40 to the substrate 22.

In addition, the side wall part 42 and the side wall part 43 areprovided to oppose each other in the X-axis direction. When the support40 has such a configuration, it is possible to simplify a manufacturingoperation for providing the light detection element 30 on the support40, and to effectively use a free space on the substrate 22.Specifically, a width of an open ceiling space of the support 40 (adistance between the side surface 42 a of the side wall part 42 and theside surface 43 a of the side wall part 43) may be set to be large, andthus the light detection element 30 is more easily installed in the basewall part 41. Further, the free space on the substrate 22 formed at bothsides of the dispersive part 21 and the molded layer 24 in the X-axisdirection may be effectively used as a bonding surface of the side wallparts 42 and 43.

Next, a description will be given on a modified example of theabove-described spectrometer 1A. In the spectrometer 1A, the contactpart of the side wall part 42 and the substrate 22 may be joined to eachother by adhesion, etc., and the contact part of the side wall part 43and the substrate 22 may be joined to each other by adhesion, etc. Inthis case, as described in the foregoing, stress or residual stressmutually applied to the support 40 and the substrate 22 due to expansionand contraction increases when compared to a case in which the contactpart of the side wall part 43 and the substrate 22 is not joined to eachother. However, it is possible to more reliably position the substrate22 and the support 40.

In addition, the contact part of the side wall part 43 and the substrate22 may be joined to each other in place of joining the contact part ofthe side wall part 42 and the substrate 22. In this case, an area of thecontact part of the side wall part 43 and the substrate 22 joined toeach other becomes smaller than an area of the contact part of the sidewall part 42 and the substrate 22 not joined to each other. Thus, anarea for joining the support 40 to the substrate 22 is suppressed. Inthis way, it is possible to further mitigate stress or residual stressmutually applied to the support 40 and the substrate 22 due to expansionand contraction. Further, the side wall part 42 and the side wall part43 may have the same width, and the width of the side wall part 43 maybe larger than the width of the side wall part 42.

In addition, as illustrated in FIG. 5, the projections 42 b and theprojections 43 b may not be formed in the side wall part 42 and the sidewall part 43. In this case, each of the side wall part 42 and the sidewall part 43 has a rectangular shape when viewed in the Z-axisdirection. In addition, alternatively, for example, the projections maybe formed in one of the side wall part 42 and the side wall part 43.Referring to FIG. 5, a wiring, etc. is not illustrated, and only thesupport 40 and the light detection element 30 are mainly illustrated,which is similarly applied to FIG. 6, FIG. 9, FIG. 13, FIG. 16, and FIG.17 used for description below.

In addition, as illustrated in FIG. 6, widths of the projections 42 band 43 b of the side wall parts 42 and 43 (lengths in the X-axisdirection) may be set to be larger than those in a case illustrated inFIG. 1, FIG. 2, and FIG. 4. That is, sizes of the widths of theprojections 42 b and 43 b are not particularly restricted. Further, asillustrated in FIG. 6, the width of the projection 42 b of the side wallpart 42 may be larger than the width of the projection 43 b of the sidewall part 43. Furthermore, on the contrary, the width of the projection43 b of the side wall part 43 may be larger than the width of theprojection 42 b of the side wall part 42. That is, the width of theprojection 42 b of the side wall part 42 and the width of the projection43 b of the side wall part 43 may be the same or different from eachother. In addition, as illustrated in FIG. 6, a width of the side wallpart 42 may be the same as a width of the side wall part 43.

Second Embodiment

As illustrated in FIG. 7, FIG. 8, and FIG. 9, a spectrometer 1B differsfrom the above-mentioned spectrometer 1A mainly in that a cutout 42 ehaving a bottom face 42 c and a side face 42 d is formed at an end partof a side wall part 42 on a stem 4 side. A bottom face 42 f of thecutout 42 e is continuously formed to surround an outside of a contactpart of the bottom face 42 c of the side wall part 42 and a surface 22 aof a substrate 22 (a portion of an outer edge part of the substrate 22).That is, the portion of the outer edge part of the substrate 22 in adispersive element 20 is fit to the cutout 42 e. Similarly, a cutout 43e having a bottom face 43 c and a side face 43 d is formed at an endpart of a side wall part 43 on the stem 4 side. A bottom face 43 f ofthe cutout 43 e is continuously formed to surround an outside of acontact part of the bottom face 43 c of the side wall part 43 and thesurface 22 a of the substrate 22 (a portion of the outer edge part ofthe substrate 22). That is, the portion of the outer edge part of thesubstrate 22 in the dispersive element 20 is fit to the cutout 43 e.

In the spectrometer 1B, similarly to the surface 22 b of the substrate22, the bottom faces 42 f and 43 f of the cutouts 42 e and 43 e are notjoined to an inner surface 4 c of the stem 4 by adhesion, etc. That is,an optical unit 10B is movable with respect to the stem 4 in a contactpart of the optical unit 10B and the stem 4 (a portion in which theinner surface 4 c of the stem 4 touches the surface 22 b of thesubstrate 22 or the bottom faces 42 f and 43 f of the cutouts 42 e and43 e).

According to the spectrometer 1B configured as described above, effectbelow is obtained in addition to the effect in common with theabove-described spectrometer 1A. That is, in the spectrometer 1B, adispersive part 21 is easily positioned with respect to a lightdetection element 30 through a support 40A by fitting the portions ofthe outer edge part of the substrate 22 to the cutouts 42 e and 43 e.

Third Embodiment

As illustrated in FIG. 10, a spectrometer 1C differs from theabove-mentioned spectrometer 1B mainly in that a dispersive element 20is separated from a stem 4. Specifically, in an optical unit 10C of thespectrometer 1C, a surface 22 b of a substrate 22 of the dispersiveelement 20 on the stem 4 side is positioned on the inside of a support40B having a hollow structure (that is, the opposite side from the stem4) from a bottom face 42 f of a cutout 42 e and a bottom face 43 f of acutout 43 e substantially flush with each other. In this way, a space isformed between an inner surface 4 c of the stem 4 and the surface 22 bof the substrate 22 of the dispersive element 20 on the stem 4 side.

According to the spectrometer 1C configured as described above, effectbelow is obtained in addition to the effect in common with theabove-described spectrometer 1A. That is, in the spectrometer 1C, thedispersive element 20 is supported by the support 40B while beingseparated from the stem 4, and thus it is possible to inhibit heat fromaffecting a dispersive part 21 from the outside through the stem 4.Therefore, it is possible to suppress deformation of the dispersive part21 (for example, a change of a grating pitch, etc.) resulting from atemperature change, and to further reduce a wavelength shift, etc.

Fourth Embodiment

As illustrated in FIG. 11, FIG. 12, and FIG. 13, a spectrometer 1Ddiffers from the above-mentioned spectrometer 1A mainly in that asupport 50 in an optical unit 10D is a hollow structure including a basewall part 41, a pair of side wall parts 52, and a pair of side wallparts 53. Specifically, the pair of side wall parts 52 is disposed tooppose each other in an X-axis direction, and the pair of side wallparts 53 is disposed to oppose each other in a Y-axis direction. Each ofthe side wall parts 52 and 53 is disposed to erect from a side of adispersive part 21 to a stem 4, and supports a base wall part 41 whilesurrounding the dispersive part 21. That is, a bottom face 52 a which isan end part of each side wall part 52 on the stem 4 side and a bottomface 53 a which is an end part of each side wall part 53 on the stem 4side continue while being substantially flush with each other along anouter edge of a substrate 22.

In the spectrometer 1D, the bottom faces 52 a and 53 a of the respectiveside wall parts 52 and 53 touch a surface 22 a of the substrate 22. Thebottom faces 52 a and 53 a of the respective side wall parts 52 and 53may be joined to the whole surface 22 a of the substrate 22 in order tostabilize positioning of the support 50 with respect to the substrate22, or partially joined to the substrate 22 in a portion of a contactpart of the respective side wall parts 52 and 53 and the substrate 22 (aportion in which the bottom faces 52 a and 53 a of the respective sidewall parts 52 and 53 touch the surface 22 a of the substrate 22) inorder to mitigate stress or residual stress mutually applied to thesupport 50 and the substrate 22 due to expansion and contraction.

According to the spectrometer 1D configured as described above, effectbelow is obtained in addition to the effect in common with theabove-described spectrometer 1A. That is, in the spectrometer 1D,positioning of the support 50 with respect to the substrate 22 isstabilized by the pair of side wall parts 52 and the pair of side wallparts 53 which support the base wall part 41 while surrounding thedispersive part 21. Herein, even though a width of the side wall part 52is the same as a width of the side wall part 53 in the spectrometer 1D,the width of the side wall part 52 may be different from the width ofthe side wall part 53.

Fifth Embodiment

As illustrated in FIG. 14, FIG. 15, and FIG. 16, a spectrometer 1Ediffers from the above-mentioned spectrometer 1A mainly in that a pairof side wall parts 62 and 63 is disposed to oppose each other in aY-axis direction rather than an X-axis direction in a support 60. Thesupport 60 is a hollow structure including a base wall part 41 disposedto oppose a stem 4 in a Z-axis direction, and a side wall part (firstwall part) 62 and a side wall part (second wall part) 63 disposed tooppose each other in the Y-axis direction. The side wall parts 62 and 63are disposed to erect from a side of a dispersive part 21 to the stem 4,and support the base wall part 41 at both sides interposing thedispersive part 21 therebetween in the Y-axis direction.

At both end sides of a side surface 62 a forming an inner end part ofthe side wall part 62 in the X-axis direction, projections 62 b areformed to protrude to a side at which the dispersive part 21 is disposedwith respect to the side surface 62 a (that is, the inside of thesupport 60 which is a hollow structure). The projections 62 b extend inthe Z-axis direction. Similarly, at both end sides of a side surface 63a forming an inner end part of the side wall part 63 in the X-axisdirection, projections 63 b are formed to protrude to a side at whichthe dispersive part 21 is disposed with respect to the side surface 63 a(that is, the inside of the support 60 which is a hollow structure). Theprojections 63 b extend in the Z-axis direction. When the projections 62b and 63 b are formed in the side wall parts 62 and 63, positioning ofthe support 60 with respect to the substrate 22 is stabilized.

In the spectrometer 1E, bottom faces 62 c and 63 c of the side wallparts 62 and 63 touch a surface 22 a of the substrate 22. The bottomfaces 62 c and 63 c of the side wall parts 62 and 63 may be joined tothe whole surface 22 a of the substrate 22 in order to stabilizepositioning of the support 60 with respect to the substrate 22.Alternatively, the bottom faces 62 c and 63 c of the side wall parts 62and 63 may be partially joined to the substrate 22 in a portion of acontact part of the side wall parts 62 and 63 and the substrate 22 (aportion in which the bottom faces 62 c and 63 c of the side wall parts62 and 63 touch the surface 22 a of the substrate 22) in order tomitigate stress or residual stress mutually applied to the support 60and the substrate 22 due to expansion and contraction.

According to the spectrometer 1E configured as described above, effectbelow is obtained in addition to the effect in common with theabove-described spectrometer 1A. As described in the foregoing, theX-axis direction is a direction in which the grating grooves of thegrating pattern 24 a are arranged, and is a direction in which portionsfor detecting lights having different wavelengths are arranged in thelight detection part 31. Therefore, the Y-axis direction perpendicularto the X-axis direction may be a direction in which an influence on awavelength shift amount is small when a position shift occurs. Herein,in the spectrometer 1E, the side wall part 62 and the side wall part 63are provided to oppose each other in the Y-axis direction in which aninfluence on a wavelength shift amount is small when a position shiftoccurs. In this way, when stress or residual stress mutually applied tothe support 60 and the substrate 22 due to expansion and contractionoccurs, a position shift of the dispersive part 21 and the lightdetection part 31 in a light detection element 30 in the X-axisdirection may be effectively suppressed. Therefore, a wavelength shiftamount may be further reduced.

In addition, as illustrated in FIG. 17, the projections 62 b and theprojections 63 b may not be formed in the side wall part 62 and the sidewall part 63. In this case, each of the side wall part 62 and the sidewall part 63 has a rectangular shape when viewed in the Z-axisdirection. In addition, alternatively, projections may be formed in onlyone of the side wall part 62 and the side wall part 63.

While the first to fifth embodiments of the present invention areexplained in the foregoing, the present invention is not limited to theabove-mentioned embodiments. For example, the lead pins 3 are notrequired to be electrically connected to the second terminal parts 12 bof the wiring 12 while being inserted through the projections 11 as inthe spectrometers 1A, 1B, 1C, 1D, and 1E. By way of example, adepression may be formed in the projection 11 so as to open to the stem4 side, and an end part of the lead pin 3 may be placed into thisdepression. In this case, the second terminal part 12 b may be exposedto the inner surface of the depression, and the lead pin 3 and thesecond terminal part 12 b may be electrically connected to each other inthe depression. Such a configuration can also securely and easilyachieve the electrical connection between the lead pins 3 and the secondterminal parts 12 b and the positioning of the optical units 10A, 10B,10C, 10D, and 10E with respect to the package 2.

In addition, the above-described configurations of the spectrometers maybe combined with each other within a possible range. For example, in thespectrometers 1A, 1D, and 1E (including various modified examplesthereof), it is possible to adopt a configuration in which a cutout isprovided in an end part of a side wall part of a support on a stem sideas in spectrometer 1B, or to adopt a configuration in which a substrateand a stem are separated from each other as in spectrometer 1C.

The stoppers 3 a provided in the lead pins 3 are not limited to thoseformed like flanges. It is not always necessary for the lead pins 3 tobe provided with the stoppers 3 a. In addition, a member other than thelead pins 3 (for example, a columnar member) may be used as the fixingmember for securing the optical unit to the stem 4. In addition, thesupport may not have the wiring, and may not be the molded interconnectdevice (MID). In this case, for example, the lead pins 3 may be directlyelectrically connected to the terminal 34 of the light detection element30 using wire bonding.

REFERENCE SIGNS LIST

1A, 1B, 1C, 1D, 1E: spectrometer, 2: package; 3: lead pin (fixingmember); 4: stem; 5: cap; 6: light entrance part; 10A, 10B, 10C, 10D,10E: optical unit; 11: projection; 20: dispersive element: 21:dispersive part; 22: substrate; 30: light detection element; 40, 40A,40B, 50, 60: support; 41: base wall part; 42, 43, 52, 53, 62, 63: sidewall part; 46: light transmission hole (light transmission part); L1,L2: light.

The invention claimed is:
 1. A spectrometer comprising: a package havinga stem and a cap provided with a light entrance part; and an opticalunit disposed on the stem inside the package, wherein the optical unitincludes a dispersive element having a dispersive part configured todisperse and reflect light entering the package from the light entrancepart, a light detection element having a light detection part configuredto detect the light dispersed and reflected by the dispersive part, anda support configured to support the light detection element such that aspace is formed between the dispersive part and the light detectionelement, wherein the support includes a base wall part disposed tooppose the stem, the light detection element being secured to the basewall part, and a side wall part disposed to erect to the stem, the sidewall part supporting the base wall part, wherein the side wall partincludes a first wall part and a second wall part opposing each other,and a first projection is formed in a first side surface forming aninner end part of the first wall part, the first projection protrudingto a side at which the dispersive part is disposed with respect to thefirst side surface.
 2. The spectrometer according to claim 1, wherein asecond projection is formed in a second side surface forming an innerend part of the second wall part, the second projection protruding to aside at which the dispersive part is disposed with respect to the secondside surface.
 3. The spectrometer according to claim 2, wherein aprotruding width of the first projection is larger than a protrudingwidth of the second projection.
 4. The spectrometer according to claim1, wherein the dispersive element includes a substrate, the dispersivepart is provided on the substrate, the side wall part is joined to thesubstrate in a portion of a contact part of the side wall part and thesubstrate.
 5. The spectrometer according to claim 4, wherein an area ofa contact part of the first wall part and the substrate is larger thanan area of a contact part of the second wall part and the substrate, thefirst wall part is joined to the substrate in at least a portion of thecontact part of the first wall part and the substrate, and the secondwall part is movable with respect to the substrate in the contact partof the second wall part and the substrate.
 6. The spectrometer accordingto claim 4, wherein an area of a contact part of the first wall part andthe substrate is larger than an area of a contact part of the secondwall part and the substrate, the first wall part is movable with respectto the substrate in the contact part of the first wall part and thesubstrate, and the second wall part is joined to the substrate in atleast a portion of the contact part of the second wall part and thesubstrate.
 7. The spectrometer according to claim 1, wherein the firstwall part and the second wall part oppose each other in a directionparallel to a direction in which the light detection part is shiftedfrom the dispersive part when viewed in a direction in which the stemand the base wall part oppose each other.
 8. The spectrometer accordingto claim 1, wherein the dispersive element includes a substrate, thedispersive part is provided on the substrate, the first wall part andthe second wall part oppose each other in a direction perpendicular to adirection in which the light detection part is shifted from thedispersive part when viewed in a direction in which the stem and thebase wall part oppose each other, and the side wall part is joined tothe substrate in at least a portion of a contact part of the side wallpart and the substrate.